Conducting polymers (also referred to as conductive polymers) have recently become more important because of their use in, for example, electrochemical devices, chemical and optical sensors, and light emitting devices.
In the past, conductive polymers were traditionally synthesized by either chemical or electrochemical oxidation. The former is accomplished through the use of a charge transfer agent while the latter does not. Both processes can be carried out in aqueous and nonaqueous media, which incorporate hazardous and potentially environmentally damaging materials (e.g., sulfuric acid or acetonitrile).
Recently, DeSimone demonstrated that chemical oxidation can be carried out in supercritical fluids (U.S. Pat. No. 5,855,819). However, their method required the use of charge transfer agents and produced conductive polymers that exhibited poor electrical conductivity (ca. 10−5 S/cm). During the same time period, several researchers demonstrated that direct electrochemical oxidation and reduction of small molecules was possible in supercritical solvents. (Abbott, A. P.; Harper, J. C. J. Chem. Soc., Faraday Trans. 1996, 92, 3895–3898. Olsen, S. A.; Tallman, D. E. Anal. Chem. 1994, 66, 503–509. Olsen, S. A.; Tallman, D. E. Anal. Chem. 1996, 68, 2054–2061. Niehaus, D. E.; Wightman, R. M.; Flowers, P. A. Anal. Chem. 1991, 63, 1728–1732. Niehaus, D.; Philips, M.; Michael, A.; Wightman, R. M. J. Phys. Chem. 1989, 93, 6232–6236. Cabrera, C. R.; Bard, A. J. J. Electroanal. Chem. 1989, 273, 147–160. Sullenberger, E. F.; Michael, A. C. Anal. Chem. 1993, 65, 2304–2310. Dressman, S. F.; Michael, A. C. Anal. Chem. 1995, 67, 1339–1345.)
Until the development described herein, there had been no synthesis of conducting polymers utilizing solely safe components.
Furthermore, the morphology of conducting polymers synthesized in the past was such that it limited its utility, for those applications which are impacted by morphology, e.g., corrosion inhibition and dielectrics.